Unravelling the relationship between Bartonella spp. and arthropod-vectors by omics approaches and tick cell lines culture

Abstract

The genus Bartonella (Rhizobiales; Bartonellaceae) encompasses facultative intracellular Gram-negative bacteria that mainly parasitize erythrocytes and endothelial cells of mammals, and can cause zoonoses with clinical manifestations ranging from moderate to severe, depending on the Bartonella species involved and the immune status of the mammalian host. Cats, rodents and bats act as reservoirs for a great diversity of Bartonella species, many of which are zoonotic. Although these agents are mainly transmitted by hematophagous arthropod vectors (fleas, ticks, mosquitoes, flies and lice), the relationship between this group of bacteria and arthropod vectors is poorly studied. Although the flea Ctenocephalides felis is a competent vector for Bartonella henselae, the causative agent of Cat Scratch Disease, the molecular mechanisms of the interaction between B. henselae and this flea species are poorly understood. The role of ticks in the transmission of B. henselae has been recently investigated using artificial feeding systems. Although fleas act as the main vectors of bartonellae among rodents, the Siphonaptera species involved in the transmission of such agents in rodents in Brazil are unknown. Similarly, despite the great diversity of Bartonella in bats from Brazil, the vectors are still unknown. The present study aims to investigate the relationship between Bartonella and arthropods (fleas, ticks, lice and mites) through "-OMICS" approaches and culture in tick cell lines, in order to verify the possible role of these invertebrates in the transmission of Bartonella spp. More specifically, the present project aims to: i.) investigate the prokaryotic microbiome and abundance of transcripts from the digestive tract of non-fed C. felis fleas fed for 24 hours and 9 days in non-infected cats and fed for 24 hours and 9 days in cats experimentally infected with B. henselae; ii.) investigate the flea prokaryotic microbiome of C. felis, Polygenis spp. and Tunga penetrans collected in the field from dogs and cats, rodents and wild boars; iii.) investigate the prokaryotic microbiome of Amblyomma ticks and lice collected from rodents in the Pantanal, Mato Grosso do Sul, hosts in which we have recently described Bartonella machadoae sp. nov.; iv.) investigate the prokaryotic microbiome of Macronyssidae and Trombiculidae mites parasites of bats, hosts for which great diversity of Bartonella spp. has been described; v.) investigate the vector competence of Amblyomma sculptum ticks in the transmission of B. henselae between cats; vi.) investigate the ability of A. sculptum (ASE-14) and R. microplus (RBME-6) embryonic cell lines to maintain and propagate B. henselae. The present proposal will contribute to the understanding of the possible role of arthropods in the epidemiology of bartonellosis in Brazil. (AU)